You Cannot See or Smell Low Oxygen in a Tank
OSHA treats air under 19.5 percent oxygen as oxygen deficient. Nothing looks or smells different, and the only way to know is a meter.
Direct answer
OSHA treats air under 19.5 percent oxygen as oxygen deficient. Nothing looks or smells different, and the only way to know is a meter.
Normal air is about 21 percent oxygen. OSHA treats anything under 19.5 percent as oxygen deficient. When a tank drops below that, nothing looks or smells different. The only way to know is a meter.
The U.S. Chemical Safety Board says oxygen deficient air can knock a person out after one or two breaths, with no warning. At 4 to 6 percent oxygen, coma comes in under 40 seconds.
How a tank loses its oxygen
Nitrogen used to purge or unload a tank. Carbon dioxide from fermentation. Rust inside a closed steel tank. In one CSB case, a tank car of mineral oil was unloaded with nitrogen, and a railcar cleaning worker later died inside it.
Even the hatch is risky
The CSB found that over 60 percent of nitrogen asphyxiation victims were working in or next to a confined space. In one case, a worker leaned into a tank through the manway, stopped answering his coworkers, and died.
A pole camera puts your eyes inside the tank while your head stays out. The APEX Tanker Inspection Kit puts an optical zoom camera on a T pole that spans the man way, with live video on a rugged tablet. Test the atmosphere per your permit program, then inspect and record from outside. See all industrial inspection kits.
Sources: U.S. Chemical Safety Board, Hazards of Nitrogen Asphyxiation, June 2003. OSHA, 29 CFR 1910.146.
Always test the atmosphere per your site's permit program before you deploy any equipment. Zistos systems do not currently carry intrinsic safety or hazardous location certification (Class I Div 1 / ATEX). If your application requires it, let's talk; we can build the right solution together.